The hepatitis C virus (HCV) is a major causative agent of parenterally transmitted non-A, non-B hepatitis worldwide. Non-A, non-B hepatitis is now the major form of posttransfusion hepatitis in the United States. The HCV genome consists of a 94 kb positive sense RNA molecule that contains one large open reading frame capable of encoding a polyprotein of 3010 or 3011 amino acids. The HCV structural proteins, especially the nucleocapsid protein, have been found to contain broadly reactive antigenic epitopes.
Currently available assays for diagnosing HCV invention, such as the use of immune electron microscopic techniques to detect virions in feces, lack the specificity and sensitivity to be useful for clinical or epidemiological analysis.
Recently, an HCV antigen was constructed by joining three large segments of proteins (266 mers, 363 mers, and 119 mers) into one polypeptide chain (Chien et al., Proc. Nat'l Acad. Sci. USA 89:1011–10015 (1992)). Examples of successful expression of small antigenically active regions with carrier proteins also exist in the literature. However, all of these antigens lack sensitivity.
None of the above-described HCV peptides or recombinant antigens provide a sensitive and specific means for diagnosing HCV infection. Therefore, because of the lack of sensitivity and difficulty of performing the currently available tests, there exists a need for a rapid, simple, and highly sensitive and specific diagnostic test for HCV infection